Generally, a built-in self-test (BIST) is a mechanism that permits a machine to test a circuitry on its own or independently. Besides other applications, built-in self-tests are used in electronic circuits for testing the functionality of modules or subunits of the electronic circuit or the whole electronic circuit. In other words, the electronic circuit provides a function that verifies all or a portion of the internal functionality of the electronic circuit. The main purpose of BIST is to decrease the test time, reduce the complexity of external test equipment, and thereby decrease the testing costs.
Array built-in self-test (ABIST) is used to test memory arrays that are contained in electronic circuits, e.g. high-end processors. ABIST allows the memory arrays to be tested at a speed identical to or above or below the system clock using a locally generated pattern set that verifies memory array functionality.
By using ABIST many of the test equipment functions are integrated in the electronic circuit under test, eliminating the complex interfacing with external test equipment. One of the major advantages ABIST has over other means of testing memory arrays is that the operation of the test is self-contained. All of the circuitry required to execute the test at-speed is contained within the integrated circuit. Very limited external controls are needed, so ABIST can be run at all levels of packaging (wafer, module and system) without requiring expensive external test equipment.
Due to the rising complexity of memory, ABIST consumes a significant electrical power. When starting the ABIST, there is a sudden large current draw from the electronic circuit power supply leading to fluctuations of the supply voltage. The clock frequency, at which the electronic circuit is driven, depends on the supply voltage. The electronic circuit may run faster with higher voltage and slower with lower voltage.
Hence, there is a need to provide for an improved method for performing ABIST which reduces fluctuations of the electric current and/or fluctuations of electric voltage of an electric circuit.